Method and apparatus for testing elastomeric sealants



1965 D. D. BROWN ETAL 3,214,961

METHOD AND APPARATUS FOR TESTING ELASTOMERIC SEALANTS Filed Oct. 1, 1963INVENTOR. DELMONT D. BROWN JAMES H. PAX

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ATT'YS United States Patent M 3,214,961 METHOD AND APPARATUS FOR TESTINGELASTOMERIC SEALANTS Delmont D. Brown, North Baltimore, and James H.Pax,

Rudolph, Ohio, assign'ors to The D. S. Brown Company,

North Baltimore, Ghio, a corporation of Ohio Filed Oct. 1, 1963, Ser.No. 312,976 12 Claims. (Cl. 73-156) This invention, in general, relatesto testing machines and methods and, more particularly, pertains tomachines and methods useful in the testing of weather-sealing propertiesof elastomer compositions under varying temperatures and stresses. Thetesting machines and methods of the invention are particularly adaptedfor the testing of elastomer strips and caulk-type joint sealants underconditions simulating field conditions wherein said strips are employedto seal any type of expansion and compression joint.

Considerable attention has been given in recent years to the use ofcompressible strips of elastomer as seal strips in concrete joints ofhighways and bridges. These compressible, resilient strips are used toseal highway and bridge expansion and contraction joints againstintrusion of water, dirt and the like into the expansion joints. Thestrips compress and expand as the expansion and contraction jointexpands and contracts under variable climatic temperature conditions.Semisolid, caulk-type joint seals include the known asphalt orasphalt-elastomer mixtures used to seal expansion and contraction jointsas well as other caulking compositions. Caulk-type joint seals arediscussed more fully later in the specification.

The testing machines of the invention may be employed to test or screenvarious elastomer compositions in terms of their potential properties assealing strips in joints of highways, buildings, airstrips, bridges,sidewalks and the like. The machines of the invention and thestripcompressing components thereof are constructed in a manner wherebythe elastomer compositions can be subjected to conditions of approximatemaximum compression of the strips anticipated in their ultimate use ashighway seal strips at hot and cold temperatures. One of the propertiesof the strips which is determined is that of elastic recovery of thestrip after it has been subjected to maximum anticipated compression athot and cold temperatures in accord with the test procedures hereafterdescribed.

Briefly, the test machines of the invention and the stripcompressionapparatus used therewith comprises a fixed block and a movable block.The movable block is movable toward and away from the fixed block. Anelastomer strip is inserted and held between adjacent faces of the twoblocks.

The fixed block is fixedly, but preferably removably, attached to theframe of the machine. The movable block is fixedly, but preferablyremovably, attached to a movable element or plate of the machine which,in turn, is reciprocally movable by power-operated means toward and awayfrom the fixed block at a slow rate of motion.

Alternatively, both blocks may be reciprocally mounted on the machineframe, and both blocks may be driven to provide the relative reciprocalmotion of said blocks toward and away from each other to compress anddecompress the elastomer strip therebetween.

In accordance with a preferred embodiment of the invention, the twoblocks with an elastomer strip compressed therebetween may be heldtogether as a unit by a supplemental frame structure attached to theblocks after the strip has been compressed by the machine or the frameto the desired state of compression. The two blocks and the supplementalframe structure may then be removed as a unit from the machine andplaced in a hot or cold 3,214,961 Patented Nov. 2, 1965 chamber whereinthe strip in the compressed state is subjected to the desired testtemperature or temperatures.

The upper, adjacent corners of the test blocks preferably are cut awayso as to form depressions when the blocks are juxtapositioned with astrip compressed therebetween. This depression is adapted to hold a testliquid such as an antifreeze liquid, e.g., a mixture of water andethylene glycol. After the strip thas been subjected under compressionto the hot and/ or cold temperature test conditions, the blocks areslowly moved apart, e.g., by retracting the movable block away from thefixed block. When the liquid in the depression begins to leak throughbetween the joint between the sides of the elastomer strip and thecontacting face of the test block or blocks, the distance between theblocks is measured. This test measures the point at which the elasticstrip losses its scaling function in relation to the side walls of thetest blocks.

An embodiment of a test machine of the invention is illustrated in thedrawings wherein:

FIG. 1 is a perspective view thereof;

FIG. 2 is a cross-section taken on section 22 of FIG. 1;

FIG. 3 is a perspective view of a test block and frame assembly thereonwhich may be used in a portion of the test procedures of the invention;

FIG. 4 is a transverse cross-section of the test blocks at the sealleakage stage of the test procedures; and

FIG. 5 is a schematic view of a hydraulic drive for the movable plateand block.

Referring to the drawing, which illustrates a preferred embodiment ofthe invention, there is shown a flat frame plate 1. A pair of frameblocks 2, 3 are bolted by the bolts 4 to the frame plate 1 alongopposite edges thereof. The frame blocks 2, 3 are parallel and containin their inward, opposing faces grooves 5, 6. The grooves 5, 6 formslide tracks for a movable plate carrying the movable testing block,hereafter described.

In addition to the frame plate 1 and frame blocks 2, 3, the machineframe further comprises a pair of parallel frame bars 7, 8 attached tothe frame plate 1 by bolts 4. These frame bars 7, 8 are parallelled andextend across one end of the frame plate 1 transversely to the frameblocks 2, 3. The frame bars 7, 8 function as journal bars for themechanical drive hereafter described and may also support a gear reducer9 fixedly mounted on the top edges thereof at one corner of the machine.The gear reducer may be mounted at other positions, if desired. The gearreducer 9 is driven by an electric motor (not shown). The output shaftof the gear reducer has mounted thereon a drive sprocket 10. The drivesprocket 10 drives via the chain '11 a larger sprocket 12 mounted on thegear shaft 13 of the spur gear 14. The gear shaft 13 is rotatablyjournalled in the frame bars 7, 8.

The spur gear 14 rotatably drives the idler gears 15, 16, which, inturn, rotatably drive the gears 17, 18. The gear shafts 25 of idlergears 15, 16 are rotatably journalled in the frame bars 7, 8. Gears 17,18 have threaded axial, apertures threadedly engaged with the machinescrew threads 21 of rods 19, 20, respectively, the ends 19 and 20' ofwhich axially slidably are supported in holes in frame bar 8. One end ofrods 19, 20 is fixedly held by nuts 22 in tapped holes 24 in the edge ofthe movable plate 23 whereby the rods are nonrotatable. The movableplate 23 is slidably mounted .in the opposing grooves 5, 6 of the frameblocks 2, 3.

The plate 23 is reciprocated in the grooves 5, 6 by rotatably turningthe gears 17, 18 by means of the gear and chain-sprocket driveheretofore described. When the chain-sprocket drive is activated, thegears 17, 18 are rotated at equal, slow rates of rotation. As the gearsrotate, the threaded engagement thereof with the machine screw rods 19,20 causes the rods and the movable plate 23 to move in one direction orthe other, depending upon the direction of rotation of the gears 17, 18.Control means for selecting the direction of rotation of the gears 17,18 may be any conventional means, the simplest and most expedient beingreversible electric motor (not shown) for driving the gear reducer 9.

A test block 26, e.g., a concrete block, is fixedly but removablyattached to the movable plate 23 by means of bolts -27 extending throughthe block 26, a cross plate 28, and a synthetic rubber pad 29, e.g.,silicone rubber, and threadedly secured in the movable plate 23. Thetest block 26 is thus reciprocally movable with the movable plate 23.The rubber pad 29 spreads the force of bolts 27 and prevents accidentalbreakage of the concrete blocks when the bolts are tightened.

The fixed block structure of the test machine cmprises a fixed plate 30fixedly attached to and extending across the end of the frame plate 1between the frame blocks 2, 3. The stationary test block 31, e.g., aconcrete block, is fixedly attached to fixed plate 30 by means of bolts32 extending through the test block 31, a cross plate 33 and a syntheticrubber pad 34. The bolts 32 are threaded in tapped holes in the fixedplate 30 and/ or the frame plate 1. Fixed plate 30 may be supported inthe grooves and 6 and fixedly attached to frame blocks 2, 3 by bolts,welding, etc. The fixed plate 30 and movable plate 23 are spaced frombase plate 1 sufficiently to allow a shallow pan P to be placed beneaththe plates, the shallow pan being used to collect liquid leakage in thetest procedures hereafter described. Instead of a shallow pan, a liquidsensing device may be used, e.g., one with an electrical circuitincluding a timer, motor-deactivating switch, or alarm device and asensor element activating the circuit when the first drop of liquidfalls through the test joint with the seal therein.

The contiguous, upper corners of the test blocks 26, 31 have cut awaysegments 35, 36 forming a depression 37, e.g., an oval depression, whenthe blocks are juxtapositioned with the elastomer strip 39 under testcompressed therebetween. The elastomer strip is inserted between theblocks in a manner whereby the strip substantially follows the contourof the juxtapositioned upper surfaces of the blocks 26, 31. It ispreferably held in the space 38 between the blocks at a distanceslightly below, e.g., below the upper surface of the juxtapositionedblocks.

The test blocks 26, 31 have in their opposite sides inwardly-directedslots or grooves 40, 41. These slots or grooves accommodate the shanks42 of bolts 43 having on their threaded ends a threaded nut, e.g., thewingnuts 44. The shanks 42 of the bolts extend through bars or plates45, 46 positioned across opposite ends of the test block assembly (FIG.3). The bolts and bars or plates 45, 46 form frame assembly which can beattached to the test block assembly on the machine when the elastomerstrip is compressed between the test blocks 26, 31. By tightening thebars or plates 45, 46 against the ends of the test blocks, the testblock assembly with the resilient strip compressed therebetween can belocked in the frame assembly. The test block assembly can then beremoved from the machine by removing bolts 27, 32. The four holes 47,shown in the test block assembly of FIG. 3, are the holes in the testblocks 26, 31 through which said bolts extend.

The mechanical drive for moving the movable plate and movable blockthereon preferably is powered by a reversible, variable speed electricmotor. The rate of movement of the movable test block can thus becontrolled by control of the rate of revolution of the motor. A constantoutput speed motor may be used, however, if desired. Furthermore, themechanical drive may be replaced by a metal bar or bars attached at oneend to the machine frame and at the other end to the movable plate 23.The metal bar or bars are made of a metal or metal alloy which expandsand contracts linearly under increasing and decreasing temperatures,respectively. The length of the bars and the linear coeflicient ofexpansion of the metal or metal alloy determines the amount of movementof the movable plate between the temperature extremes of the test. Inthese adaptations of the invention, the test machine itself is placed inthe freezing chamber and/or heating oven employed in the test procedurein order to expand or contract the metal bars or bellows while at thesame time subjecting the elastic strip to the test temperature. Thethermally expandable and contractable metal bars may be operativelyassociated with both blocks, instead of only one block, in test machineswherein both of blocks 26, 31 are mounted on the frame, e.g., by alsomounting block 31 on movable slide plate like plate 23, for relativereciprocal motion toward each other at increasing temperatures and awayfrom each other at decreasing temperatures.

Another alternate form which can be substituted for the mechanicaldrives for the movable plate and block is a hydraulic fluid systemcomprising a conventional hydraulic chamber fixedly mounted on themachine frame with a movable piston therein. The piston rod is connectedto the movable plate. The piston and piston rod are moved in eitherdirection at the desired linear rate hydraulic force applied against theappropriate side of the piston.

A hydraulic drive is illustrated schematically in FIG. 5. The over-alltest machine structure may be substantially the same .as the testmachine embodiment of FIGS. 1 and 2 with the mechanical drive andassociated support parts therefor omitted. The movable plate 23 withmovable block 26 thereon are driven by a hydraulic system comprising ahydraulic fluid chamber 50 with a piston 51 longitudinally recipro-cabletherein. The piston rod 52 of piston 51 is attached to the movable plate23.

A pair of hydraulic fluid lines 53, '54 communicate the chamber 50 oneach side of the piston 51 with opposite sides of the piston 56 ofmaster hydraulic fluid cylinder 57. One of the lines 53, 54 has a 'bleedvalve 55 which can be adjusted to control the rate of flow of hydraulicfluid between the master cylinder and the hydraulic chamber 50 to givethe desired rate of linear movement to plate 23. The piston 56 may havea single piston rod 58 which is movable in either direction bymechanical power, e.g., a rack and pinion. The pinion may be driven by areversible motor through slip clutch to allow slip in the mechanicaldrive when the bleed valve is adjusted to allow lesser volume movementof hydraulic fluid than the movement provided by operation with theclutch at minimum slip and avoid overload in the hydraulic pressure.Alternatively, the piston 56 may also have a second, oppositely directedpiston rod 59, each of which piston rods 58, 59 coupled to a powersource, moving the respective rods in opposite directions. An example ofthe latter is coil tension springs 60, 61 attached to each rod withmultiple advantage mechanism, a ratchet and pawl mechanism of theautomobile bumper jack type for individually and manually tensioningeach spring. Each spring in the untensed state should have sufficientsag so as not to become tensed while the other spring is moving thepiston 56. The hydraulic fluid should be one having good fluidproperties at cold temperatures, e.g., in the range of the 0 F. to -65F. temperatures used in the test procedures herein described.

The movement of the test blocks toward each other in the heating oraging cycle of the test is not of great or critical importance, however.The oven treatment is primarily an accelerated aging treatment of theelastomer seal strip, and it can be done with the strip held in thepreviously described frame assembly to conserve space in the oven.Before allowing the aged seal strip to ex-- pand, it is taken down tothe cold test temperature. The prime purpose of this type of test is thecollection of data on cold flexibility movement or resilience of therubber in cold temperatures, compression and permanent set due to theaging, and the determination of positive sealing by having a liquid ontop of the seal utilizing the actual, finished seal.

When testing elastomer strips as highway or bridge concrete joint seals,the test blocks 26, 31 preferably are concrete blocks so that thesurfaces of the blocks which contact the elastomer strips are comparabletexture to concrete highway or bridge sections. Where the strips beingtested are intended for use as sealing strips or gaskets between othertypes of surfaces, other materials may be selected as the test blocks.Where relatively smooth surfaces are involved, metal blocks or the likemay be used.

Testing methods Elastomer seal strips, as a general rule, are mostcritically adversely affected in terms of their elastic recovery orresilience upon lateral expansion of the strip at cold temperatures. Thestrips have a poorer elastic recovery from compression when cold thanwhen warm. Accordingly, the test procedures herein set forth are madewith the objective of testing the strips by simulating the actual oranticipated field conditions at which the sealing function of stripusually breaks down.

As an example of an actual field condition for a highway in which theexpansion and contraction joints are sealed or to be sealed by theelastomer strip under test, assume a warm, sunny winter day in which theconcrete sections are warmed by both the warm air and by radiation heatof the sun. The joints are well contracted under this condition. Thereis a sudden temperature drop in late afternoon or early evening to atemperature in the range of 0 F. to 65 F. The elastomer strips becomecold quickly, and the highway sections cool and contract. The jointsbegin to open, and the cold elastomer strips must expand laterally tomaintain the seal between the side walls of the strips and the sidewalls of the joints. This is a critical area in which the strip mustexpand laterally under most adverse conditions in terms of its lateralelastic recovery.

The tests hereafter described simulate such conditions and preferablyare even somewhat more severe than would be the worst anticipated fieldcondition. The collection of data on the sealing qualities of the stripwith lateral expansion of the strip at the selected cold test conditionpreferably is made first on the strip before it is subjected to aging byheat. The strip is then aged at high temperature in an oven with thestrip under about maximum anticipated compression. The oven temperatureis ordinarily above maximum anticipated field temperature in order toaccelerate the elastomer aging process and shorten the total test time.The reason why the strip is compressed at about maximum anticipatedcompression during the aging step is that in field use the strip wouldbe under the same conditions when it is at its highest temperature, thejoints being contracted or closed the greatest amount when the highwayconcrete sections are the hottest. Our test methods, however, can beused, though not as effectively in terms of duplication of fieldconditions for measuring the effect of permanent set due to heat agingof the elastomer, with the aging done at substantially less than maximumanticipated compression.

After the heat aging step, the strip is tested again at the coldtemperature by the cold temperature procedure previously described. Bycomparing the data obtained both prior to and after aging for percent ofrecovery of the original width of the strip under cold temperaturelateral expansion of the strip as the test machine joint expands up tothe point of loss of seal against liquid penetration, the effect ofaging on the strip can be measured.

This data can be very helpful in future research to find modified or newcompounding measures for vulcanizable elastomer compositions and/ ormodification of the physical structures of the strips to improve theover-all quality of the strips.

The testing of the suitability of a particular elastomer strip as aconcrete joint seal or the like is conducted on the machine illustratedin the drawings by the following procedure.

The blocks 26, 31 are separated enough to insert the elastomer strip 39therebetween with the upper surface of the strip substantially flushwith or slightly below the contour of the adjacent, upper surfaces ofthe blocks. The movable plate 23 and block 26 are moved toward the block31 by the mechanical drive system of the machine until the strip 39 iscompressed to about the maximum amount of compression anticipated infield use. At this stage, the frame assembly shown in FIG. 3 may beassembled and tightened about the test blocks. The bolts 27, 32 then maybe removed, and the test block and frame assembly thereabout are liftedfrom the test machine, the elastomer strip 39 still being in the stateof maximum anticipated compression. As an alternative, the entire testmachine (preferably excluding the electric motor) may be used in thisportion of the test, and the steps of frame assembly and removal of thetest blocks may be omitted.

The test machine or the test block-frame assembly, as the case may be,is brought to a subfreezing temperature in the range of about 0 F. to 65F. in order to subject the compressed strip to a selected, subfreezingtemperature for a period of about 18-72 hours in a cold box,refrigerated chamber or room, etc.

Then a liquid which will not freeze at the test temper ature is placedin the depression 37. A mixture such as a 50-50 mixture of water andethylene glycol may be used, for example. Preferably in the cold box,refrigerated chamber or room, etc., and in any case without allowingappreciable warming of the cold test blocks and elastomer strips abovethe subfreezing temperature to which the elastomer seal strip issubjected and with the blocks 26, 31 remounted on the machine (ifremoved for the cold temperature segment of the test), the mechanicaldrive is activated to move slowly the movable block 26 away from thefixed block 31. A linear movement of about to 1 /2" per hour, in mostcases about to Vs per hour, may be selected. The movement is stoppedwhen the liquid L in the depression 37 begins to leak between thecontacting wall or walls of test blocks 26, 31 and the strip 39 (FIG.4). The distance between the blocks 26, 31 is measured to ascertain thedegree of elastic recovery of the elastomer strip up to the point whereits liquid-tight seal with the test blocks is lost.

The same strip is then again compressed to the smallest widthanticipated in actual service. The frame assembly (FIG. 3) is assembledand tightened about the test blocks, and the test block-frame assemblyis removed from the machine. The removed unit, with the elastomer sealstrip under compression, is placed in a heating chamber or oven for anaccelerated aging of the elastomer. The aging temperature may be aselected temperature in the range of ISO-230 F., and the selected agingtime may be in the range of 48-120 hours.

After the accelerated aging step, the unit is placed, with the strip 39still in its compressed state, in a refrigerated room or chamber whereinthe subfreezing temperature portion of the test, above described, isrepeated at a temperature and time in the ranges above stated. With thetest blocks remounted on the test machine in the cold box, refrigeratedchamber or room, etc., the liquid L is poured into the depression 37,and the block 26 is retracted slowly away from block 31 until leakagebetween the test block or blocks and the elastomer seal strip is notedat the cold temperature of the test.

As an alternative test procedure after the accelerated aging, a dynamictype test procedure can be used wherein the machine with the test blocksthereon and the liquid L always in the depression can be moved to a coldatmosphere to -65 F.) then to a hot atmosphere (95- 140 F.), and thenback to the cold atmosphere. The elastomer seal strip is given thecalculated or anticipated maximum and minimum compression or expansionbetween the test blocks in the two respective atmospheres. The leakageof the seal is ascertained at the critical stage, i.e., in the coldatmosphere, as aforedescribed.

By conducting the foregoing tests on a number of different types ofelastomer compositions and/or structural styles of elastomer sealstrips, and by measuring for each seal strip tested its initial,uncompressed width, compressed width, time and temperature of the ovenaging and subfreezing steps, rate of separation of the test blocks,distance between blocks at the first sign of a leak between the seal andthe test blocks, and width of the seal after it is released fromcompression (a) immediately, (b) after 30-60 minutes at room temperatureand (c) after 24 hours at room temperature, a compilation of data isassembled from which the better-performing elastomer strip or strips canbe selected for further laboratory tests or field study.

As a specific example, with neoprene seal strips for concrete highwayexpansion joints, the test procedure above described was conducted at asubfreezing temperature of 30 F. for 22 hours, at a rate of separationof the test blocks of A per hour, and at an aging temperature of 212 F.for 70 hours. The seal strip in the cold temperature expansion at 30 F.recovered 90% of its original width before leakage was detected. Alesser recovery was experienced upon cold temperature expansion afteraging.

The machine and test procedures aforedescribed may also be used toascertain the sealing properties of caulktype, semi-solid, expansion andcontraction joint seals for highways, bridges, buildings, airstrips,etc. A well known caulk-type, highway seal is the asphalt seal made bypouring hot, liquid asphalt into the joint. Upon cooling, the asphaltbecomes a semi-solid mass with cold flow properties. Similar semi-solidseals are made with mixtures of asphalt and elastomers such as naturalrubber or synthetic elastomers (e.g., butyl rubber, butadiene-styrenecopolymers, neoprene, etc.). The elastomers improve the flexibility andresilience of the asphaltic-type seal.

The caulk-type, semi-solid seals behave somewhat differently from theelastomer seals heretofore discussed in that they have little oressentially no elastic resilience when compressed. The caulk-type sealrelies upon adhesion of the caulking composition to the side walls ofthe joint to maintain the seal as the expansion and contraction jointopens. In theory, the seal is stretched as the joint opens in coldweather and returns to the normal state as the joint contracts in hotweather. In practice, however, the caulking seal usually either pullsaway from the one or both of the side walls of the joint or cracks downthe middle. These cracks in the seals themselves or between the seal andthe side walls of the joints fill with highway dirt and other solids,reducing the compressibility of the caulking seal. The ultimate resultof build up of such solids in the cracks, if left uncorrected, is ajoint seal filled with enough incompressible solids so that the sealwill not compress enough in hot weather, as the concrete highwaysections or the like expand, to take up the expansion. Pressures in theconcrete sections develop sufficient magnitude to cause the concrete tobreak. Another adverse effect is known as roping, which is a problemwith caulking seals such as polysulfide rubber caulking seals.

It will be apparent, therefore, that laboratory testing of caulking-typeseals, as well as the laboratory testing of elastomer, dry-type sealsheretofore discussed, is of practical value. The tests are conducted byessentially the same procedure as the cold temperature (0 F. to 65 F.)test. Aging of the seal at high temperature, of course, has no purposewith asphalt-type seals, but the 55 seal may be subjected to and/ortested at high temperatures (e.g., l0()l40 P.) if desired.

As an example of a testing procedure with a caulkingtype seal, hotasphalt is poured into a joint between concrete blocks 26, 31 with thejoints spaced apart at the smallest, anticipated spacing betweenconcrete sections of a highway or bridge joint. The test machine isplaced in a cold box, refrigerated room, etc., maintained at apreselected temperature in the range of 0 F. to F., e.g., 30 F. When theconcrete blocks and seal are at equilibrium with the cold atmosphere,the test machine is activated. Prior thereto, antifreeze liquid L isplaced in the depression 37. Movable block 26 moves away from block 31at a slow, predetermined rate. When the liquid seeps through the seal,the test is stopped. The spacing between the concrete blocks at thepoint of loss of liquid seal is recorded. Other observations of valuewku'ch can be made during the test are notations as to surface cracksformed in the seal as the joint expands, cause of loss of liquid seal(e.g., separation of a wall or walls of the concrete block and thecaulking seal or a break in the middle of the seal), and like data whichwill be of value in future research for improving performance of theseal.

Thus, the test machines and test methods herein defined provided dynamictest conditions simulating field use of elastomer strips as joint sealsbetween expanding and contracting sections. Considerable time andexpense can be saved by the employment thereof in screening andevaluating various elastomer compositions and/ or various elatsomerstrip structural styles for a given field use. Similar, valuable,experimental data can be obtained in tests with caulk-type, semi-solidseals.

The invention is hereby claimed as follows:

1. A testing machine comprising a frame, a first block and a secondblock mounted on said frame, means on said frame mounting said blocksfor relative, horizontal reciprocal movement toward and away from eachother, and means for providing slow, reciprocal, relative movementbetween said blocks toward and away from each other to compress anddecompress, respectively, an elastomer strip between adjacent faces ofsaid blocks, the upper surfaces of said blocks being recessed to form aliquidreceiving depression in said upper surfaces with said stripcompressed between said blocks at said depression.

2. A testing machine as claimed in claim 1 wherein said blocks areconcrete blocks.

3. A testing machine comprising a frame including a pair of spaced,parallel frame members, horizontal slide means on said frame members, afirst block mounted on said frame and extending between said framemembers, a plate extending between said frame members and slidable onsaid slide means toward and away from said first block, a second blockmounted on said plate, and me chanical drive means coupled to said platefor moving said plate and second block at a slow linear speed away fromsaid first block, the upper surfaces of said blocks being recessed toform a liquid-receiving depression in said upper surfaces with saidstrip compressed between said blocks in said depression.

4. A machine as claimed in claim 3 wherein said mechanical drive meansincludes a threaded rod fixedly attached to said movable plate, and arotatable drive member threadedly engaged with said rod.

5. A machine as claimed in claim 3 wherein said blocks have alignedgrooves in opposite side walls of each of said blocks, said groovesadapted to receive members of a frame assembly adapted to be used toclamp said blocks together with an elastomer strip compressedtherebetween, means releasably attaching said first block to said frame,and means releasably attaching said second block to said movable plate.

6. An assembly used in testing properties of elastomer strips comprisinga first concrete block, a second concrete block, an elastomer stripcompressed between opposing faces of said blocks, and a frame assemblyabout said blocks holding said blocks together with said stripcompressed therebetween, the upper surfaces of said blocks beingrecessed to form a liquid-receiving depression in said upper surfaceswith said strip compressed between said blocks in said depression.

7. A testing machine comprising a frame including a pair of spaced,parallel, frame members, horizontal slide means on said frame members, afirst block mounted on said frame and extending between said framemembers, a plate extending between said frame members and slidable onsaid slide means toward and away from said first block, a second blockmounted on said plate, and fluid-driven drive means coupled to saidplate for moving said plate and second block at a slow linear speed awayfrom said first block, the upper surfaces of said blocks being recessedto form a liquid-receiving depression in said upper surfaces with saidstrip compressed between said blocks in said depression.

8. A process for testing the joint scaling properties of elastomer sealstrips which comprises compressing between a pair of compression membersan elastomer strip, subjecting said elastomer strip in the compressedstate to a subfreezing temperature, forming a pool of liquid, which doesnot freeze at said subfreezing temperature, above and in contact withthe joints between the sides of said compressed strip and saidcompression members, slowly decompressing said strip at a subfreezingtemperature by slowly separating said members until liquid from saidliquid pool seeps through one of said joints, and measuring the spacingbetween said compression members when said liquid seeps therethrough.

9. A process for testing the joint sealing properties of elastomer sealstrips which comprises compressing an elastomer strip between a pair ofcompression members, aging said strip in the compressed state in an ovenat an elevated temperature, subjecting said strip in the compressedstate to a subfreezing temperature, forming a pool of liquid, which doesnot freeze at said subfreezing temperature, above and in contact withthe joints between the sides of said compressed strip and saidcompression members, slowly decompressing said strip at a subfreezingtemperature by slowly separating said members until liquid from saidliquid pool seeps through one of said joints, and measuring the spacingbetween said compression members when said liquid seeps therethrough.

10. A process as claimed in claim 8 wherein said subfreezing temperatureis in the range of 0 F. to F.

11. A process as claimed in claim 9 wherein said subfreezing temperatureis in the range of 0 F. to 65 F., and said elevated temperature is inthe range of 230 F.

12. A process for testing the joint sealing properties of semi-solid,caulking seals which comprises forming a semi-solid, caulking sealbetween a pair of closely spaced members, subjecting said members andseal to a sub freezing temperature, forming a pool of liquid, which doesnot freeze at said subfreezing temperature, above and in contact withthe joints between said seal and said members, slowly widening the spacebetween said members at a subfreezing temperature until liquid from saidliquid pool seeps through the seal formed between said members by saidsemi-solid, caulking seal, and measuring the spacing between saidcompression members when said liquid seeps therethrough.

References Cited by the Examiner UNITED STATES PATENTS 2,283,743 3/42Lessig 7391 X 2,933,921 4/60 Gloor 7393 3,062,009 11/62 Thiele 7392 XRICHARD C. QUEISSER, Primary Examiner.

DAVID SCHONBERG, Examiner.

8. A PROCESS FOR TESTING THE JOINT SEALING PROPERTIES OF ELASTOMER SEALSTRIPS WHICH COMPRISS COMPRESSING BETWEEN A PAIR OF COMPRESION MEMBERSAN ELASTOMER STRIP, SUBJECTING SAID ELASTOMER STRIP IN THE COMPRESSEDSTATE TO A SUBFREEZING TEMPERTURE, FORMING A POOL OF LIQUID, WHICH DOESNOT FREEZE AT SAID SUBFREEZING TEMPERATURE, ABOVE AND IN CONTACT WITHTHE JOINTS BETWEEN THE SIDES OF SAID COMPRESSED STRIP AND SAIDCOMPRESSION MEMBERS, SLOWLY DECOMPRESSING SAID STRIP AT A SUBFREEZINGTEMPERATURE BY SLOWLY SEPARATING SAID MEMBERS UNITL LIQUID FROM SAIDLIQUID POOL SEEPS THROUGH ONE OF SAID JOINTS, AND MEASURING THE SPACINGBETWEN SAID COMPRESSION MEMBERS WHEN SAID LIQUID SEEPS THERETHROUGH.